[runtime] support new Proxy() instead of Proxy.create and install getPrototypeOf trap

src/runtime/runtime-proxy.cc

Index: src/runtime/runtime-proxy.cc
diff --git a/src/runtime/runtime-proxy.cc b/src/runtime/runtime-proxy.cc
index 4699647b8013a7d30c633b3192089d4ecc7a027a..b1ed2d1c7d4ee5aa6999f24274e5b6f8bccf1d03 100644
--- a/src/runtime/runtime-proxy.cc
+++ b/src/runtime/runtime-proxy.cc
@@ -13,11 +13,17 @@ namespace internal {
 
 RUNTIME_FUNCTION(Runtime_CreateJSProxy) {
   HandleScope scope(isolate);
-  DCHECK(args.length() == 2);
-  CONVERT_ARG_HANDLE_CHECKED(JSReceiver, handler, 0);
-  CONVERT_ARG_HANDLE_CHECKED(Object, prototype, 1);
-  if (!prototype->IsJSReceiver()) prototype = isolate->factory()->null_value();
-  return *isolate->factory()->NewJSProxy(handler, prototype);
+  DCHECK(args.length() == 3);
+  CONVERT_ARG_HANDLE_CHECKED(JSProxy, instance, 0);
+  CONVERT_ARG_HANDLE_CHECKED(JSReceiver, target, 1);
+  CONVERT_ARG_HANDLE_CHECKED(Object, handler, 2);
+  // TODO(cbruni): Remove once we don't support JSProxy.fix
+  instance->InitializeBody(instance->map()->instance_size(), Smi::FromInt(0));
+  if (!handler->IsJSReceiver()) handler = isolate->factory()->null_value();
+  instance->set_target(*target);
+  instance->set_handler(*handler);
+  instance->set_hash(isolate->heap()->undefined_value(), SKIP_WRITE_BARRIER);
+  return *instance;
 }